A Kansas-based anti-gay Baptist church began its promised three-day assault on Brooklyn with a brief rally this afternoon at a Fort Greene high school, two days before they vow to picket at three Jewish synagogues in Brownstone Brooklyn over those institutions’ apparent godlessness.

About five members of the Westboro Baptist Church, whose mission is represented clearly in its Web site address, http://www.godhatesfags.com, rallied for about 15 minutes outside Brooklyn Technical HS, holding signs reading, “Fags are beasts” and “God is your enemy.”

But the students were ready for them, holding a far-better-attended counter-protest. There was no violence, as police kept both sides apart.

“I find it disgusting that people can come to a public school, especially one as diverse as Brooklyn Tech, and express hate,” said James, 17, who declined to give his last name.

It is unclear why the church chose Brooklyn Tech, but its Web site suggested that the school teaches that “it’s OK to be gay.”

“WBC will teach the rebels of Brooklyn what good looks like, and you had better behave,” the church said.

During the protest, students remained across the street from the protesters, some yelling, “Go home!” and holding signs and stickers promoting tolerance. Students were angry, but peaceful, about the church group’s presence.

“Hating people is not really a good thing,” said Ahmed Muhsin, 16, a junior. “[The group] is trying to get attention. It’s really stupid. I don’t know why they’re doing it.”

Not only students, but some adults were part of the counter-protest against the church group.

“We are a diverse community,” said Jennifer Marik, a Clinton Hill resident. “We welcome everyone. Their hate does not belong in my city.”

Brooklyn Tech’s principal Randy Asher couldn’t explain why the anti-gay and anti-Jewish protesters targeted his school. He surmised that Tech is one of the largest schools in the city with a diverse and multicultural student body.

“I’m disappointed that anybody would advocate hate,” he said. “My students responded accordingly with a counter-protest. They were calm and civil about it. They were angered and frustrated by the statements by the other group.” He also added, “These are some of the best students in the country so I would expect no less.”

The Fort Greene rally came two days before the same bigots will rally on Saturday in front of Congregation Beth Elohim on Eighth Avenue in Park Slope at 9:45 am, at Union Temple on Eastern Parkway in Prospect Heights at 10 am and the Kane Street Synagogue in Cobble Hill at 12:30 pm on the eve of Yom Kippur, the holiest day on the Jewish calendar.

Church spokeswoman Shirley Phelps-Roper said the rallies were not anti-Jewish or anti-gay.

“How about we call it an ‘Obey your God’ rally?” she told The Brooklyn Paper. “You Jews and gays have got to put away your false gods, your idols and your filthy way of life.”

She added that “God hates the disobedient.”

“We picked these weekends because these are the high holidays,” she said. “You Jews broke the covenant with God. The beast is going to bring the nations to march upon Jerusalem. Your houses will be destroyed and your women ravaged. It’s going to make the Holocaust, the Babylonian captivity and the destruction of the Temple look like a tea party.”

The Anti-Defamation League, which has been monitoring the group for several years, said that Westboro tends to protest groups that “they think support homosexuality or otherwise subvert what they believe is God’s law.”

That even extends to the families of dead soldiers. Church members have made headlines for protesting at the funerals of military personnel, claiming that the soldiers’ deaths were dishonorable because they fought to defend a country that allows homosexuals to openly enjoy their sexuality.

Rabbi Andy Bachman of Congregation Beth Elohim prepared his congregation for the assault in a letter sent late on Tuesday that praised his temple as a “community that celebrates the strength of diversity” and a place “for individuals and families of all backgrounds to grow and to learn” — a possible reference to the focus of the Baptist group’s anger.

The next day, Bachman told The Brooklyn Paper that he had no idea why the Baptist fringe group is targeting local shuls on Saturday.

“If you look at their Web site, they are equal opportunity haters,” he said. “They are living inside some kind a time warp in which they feel they have the legitimacy to speak on an ancient Biblical notion of what God wanted or, more precisely, what ancient people thought God wanted from humanity.

“They have ignored the last 3,000 years of development of human civilization — that’s what makes their message so shocking,” he added.

Bachman said his temple had consulted with the NYPD and other congregations that had been the target of Westboro protests and determined that the best response is to not respond at all.

“We will essentially ignore it,” he said, just a few feet from the temple’s facade, which features the names of such hardly controversial religious figures as Abraham, Joshua, Samuel, Elijah, Isaiah, Jeremiah, Ezekiel, Esther and Ruth.

He also said that the bat mitzvah ceremony of Natalie Chertoff would go on as planned.

“She’s amazing,” he said. “Here’s a teenager who’s strong and confident. And she’s seeing [the protest] as a lesson that people will attempt to do hateful things, but our eternal message as Jews is affirming life in the face of hate. That’s been our key to survival.”

Bachman said he did not anticipate violence from his congregation, but the NYPD will nonetheless be out in full force. Phelps-Roper, the Westboro spokeswoman, laughed at the suggestion that Brooklynites would react violently.

“Don’t flatter yourself, Brooklyn,” she said. “We serve the living God. You mess with us, you’ll get double destruction for what you do.”